All of the following can be used to determine a chromosome analysis of the fetus except

(Beckmann, 4/e, pp 280-281. Cunningham, 21/e, pp 755, 989-992, 1132-1133.) Fetal tissue for chromosome analysis can be obtained amniocentesis, chorionic villus sampling (CVS), percutaneous umbilical blood sampling, or direct biopsy of fetal muscle or skin. Amnio- centesis involves obtaining a sample of amniotic fluid, which contains fetal fibroblasts. Chorionic villus sampling involves taking a biopsy of the placenta. In the case of PUBS, the umbilical vein is punctured under direct ultrasound guidance near the placental origin and blood is obtained for genetic analysis. Doppler velocimetry is an ultrasound technique used to examine blood flow through the umbilical aery. IUGR has been associated with abnormal umbilical aery Doppler velocimetry. Therefore, this technique is used with other modalities such as BPP and NSTS to monitor fetal wellbeing.